Peak Flow Meters allow patients to monitor their asthma and Peak Expiratory Flow (PEF); a measurement of how fast a patient can blow out. When a pa
Peak flow meters allow people to to monitor their asthma; Peak Expiratory Flow (PEF) is a measurement of how fast someone can blow out. When you are well your PEF is higher, when the airways are narrow (as in asthma) PEF is lower.